1248results about "Angle modulation" patented technology

Systems and methods for receiving an OFDM preamble without knowledge of channel characteristics are provided. An OFDM preamble signal with frequency shifted cyclic extensions is received. Taken together the cyclic extensions form a frequency shifted version of the OFDM preamble signal. Frequency offsets and timing offsets are estimated and corrected in an efficient manner using a simple concatenation approach in the time domain, followed by a summation of the OFDM preamble signal and the concatenation after a transformation of the OFDM preamble and the concatenation into the frequency domain. Phase errors in the frequency domain are estimated and corrected after FFT transformations of the received signals. A valid preamble is detected and additional parameters for receiving subsequently transmitted OFDM symbols in a channel are extracted from the OFDM preamble. The methods are computationally efficient and robust. Receiver implementations for performing the methods in a DVB receiver are disclosed.

The present invention relates to methods and apparatus for preventing power imbalance in a multiple input multiple output (MIMO) wireless precoding system. According to one aspect of the present invention, a codebook is constructed with a first subset of codewords that are constant modulus matrices, and a second subset of codewords that are non-constant modulus matrices. A mapping scheme is established between the first subset of codewords and the second subset of codewords. When a unit of user equipment feeds back a first codeword that is a non-constant modulus matrix, the Node-B may replace the first codewords with a second codeword that is selected from the first subset of codewords and that corresponds to the first codeword in accordance with the mapping scheme.

A non-contact power supply system includes a power supply device for transmitting high frequency power and a load device which receives the high frequency power in a non-contact mode by electromagnetic induction to supply it to a load. The power supply device includes a power transmission unit having a primary power coil and an inverter circuit, an inquiry unit having at least one primary signal coil and an oscillation circuit, a signal detection unit and a control unit. The load device includes a power reception unit having a secondary power coil magnetically coupled to the primary power coil and a power conversion unit, a secondary signal coil magnetically coupled to the primary signal coil, and a response unit which is operated by electromotive force induced in the secondary signal coil. The control unit stops power transmission when no signal is detected and executes power transmission which a signal is detected.

An impulse radio communications system using one or more subcarriers to communicate information from an impulse radio transmitter to an impulse radio receiver. The impulse radio communication system is an ultrawide-band time domain system. The use of subcarriers provides impulse radio transmissions added channelization, smoothing and fidelity. Subcarriers of different frequencies or waveforms can be used to add channelization of impulse radio signals. Thus, an impulse radio link can communicate many independent channels simultaneously by employing different subcarriers for each channel. The impulse radio uses modulated subcarrier(s) for time positioning a periodic timing signal or a coded timing signal. Alternatively, the coded timing signal can be summed or mixed with the modulated subcarrier(s) and the resultant signal is used to time modulate the periodic timing signal. Direct digital modulation of data is another form of subcarrier modulation for impulse radio signals. Direct digital modulation can be used alone to time modulate the periodic timing signal or the direct digitally modulated the periodic timing signal can be further modulated with one or more modulated subcarrier signals. Linearization of a time modulator permits the impulse radio transmitter and receiver to generate time delays having the necessary accuracy for impulse radio communications.

A phase-shift based pre-coding scheme used in a transmitting side and a receiving side that has less complexity than those of a space-time coding scheme, that can support various spatial multiplexing rates while maintaining the advantages of the phase-shift diversity scheme, that has less channel sensitivity than that of the pre-coding scheme, and that only requires a low capacity codebook is provided.

A smart radio incorporating Parascan® varactors embodied within an intelligent adaptive RF front end. More specifically, this is provided for by a smart radio incorporating Parascan® varactors embodied within an intelligent adaptive RF front end that comprises at least one tunable antenna; at least one antenna null steering facility associated with said at least on tunable antenna; at least one tunable duplexer receiving the output from and providing input to said at least one antenna null steering facility; a first tunable RF filter receiving the output from said at least one tunable duplexer and providing the input to an analog to digital converter, said analog to digital converter providing the input to a digital signal processor, the output of which is input for a digital to analog converter; a second tunable RF filter receiving the analog output of said digital to analog converter and providing an input to said at least one tunable duplexer.

An apparatus includes: an affine transformer that subjects input complex IF signals I(t) and Q(t) to affine transformation according to affine transformation coefficients, and outputs compensated signals a(t) and b(t); a quadrature modulator that applies quadrature modulation on a local oscillation signal according to the compensated signals, and outputs a modulated signal (RF transmission signal); a quadrature detector that removes a carrier component from the modulated signal and outputs complex feedback signals I′ (t) and Q′ (t); and a control portion that extracts linear distortions remaining in the complex feedback signals I′ (t) and Q′ (t) as plural distortion coefficients (DC offsets of the I-phase and the Q-phase, an IQ gain ratio, and a deviation in orthogonality), and updates the current affine transformation coefficients in accordance with updating equations including the distortion coefficients to set updated affine transformation coefficients again in the affine transformation portion. It is thus possible to constantly update the distortion compensation coefficients most appropriately under operating conditions.

The present invention is directed to a system and method of remotely controlling a welding machine with command signals transmitted to the welding power source across a weld cable connecting the power source to a remote device, such a wire feeder. A transmitter transmits the control commands containing desired welding operational parameters to a receiver disposed in the power source across a weld cable also designed to carry welding power from the power source to the wire feeder.

A novel apparatus for and a method of noise and spurious tones suppression in a digital RF processor (DRP). The invention is well suited for use in highly integrated system on a chip (SoC) radio solutions that incorporate a very large amount of digital logic circuitry. The noise suppression scheme eliminates the noise caused by various on chip interference sources transmitted through electromagnetic, power, ground and substrate paths. The noise suppression scheme permits an all digital PLL (ADPLL) to operate in such a way to avoid generating the spurs that would normally be generated from the injection pulling effect of interfering sources on the chip. The frequency reference clock is retimed to be synchronous to the RF oscillator clock and used to drive the entire digital logic circuitry of the DRP. This ensures that the different clock edges throughout the system will not exhibit mutual drift. A method of improving the resolution quality of a time to digital converter within the ADPLL is also taught. The method dithers the reference clock by passing it through a delay circuit that is controlled by a sigma-delta modulator. The dithered reference clock reduces the affect on the phase noise at the output of the ADPLL due to ill-behaved quantization of the TDC timing estimation.

A geometrically modifiable resonator is comprised of a resonator disposed on a substrate, and a means for geometrically modifying the resonator. The geometrically modifiable resonator can achieve active optical and/or electronic control of the frequency response in metamaterials and/or frequency selective surfaces, potentially with sub-picosecond response times. Additionally, the methods taught here can be applied to discrete geometrically modifiable circuit components such as inductors and capacitors. Principally, controlled conductivity regions, using either reversible photodoping or voltage induced depletion activation, are used to modify the geometries of circuit components, thus allowing frequency tuning of resonators without otherwise affecting the bulk substrate electrical properties. The concept is valid over any frequency range in which metamaterials are designed to operate.

A system providing an inductive power and data link between an external transmitter and miniature internal receiver is presented. The system is suited to applications where the receiver must be of a small size and the system must consume very little power, such as an implanted biomedical device. The system is also compatible with systems where bi-directional communications are required. The novel transmitter and receiver form an improved forward data telemetry system. The transmitter consists of a Class-E converter with its optimum operating frequency being synchronously, instantaneously and efficiently altered in accordance with the data to be transmitted, thereby producing an FSK modulated magnetic field of substantially constant amplitude. The constant amplitude output allows for the continuous, data-independent transfer of power to the miniature receiver and its associated electronics. The present invention also represents an improvement over the high efficiency Class-E converters previously patented by the inventors. The receiver consists of a coil and an integrated rectifying system to recover operating power from the incident magnetic field, as well as an FSK demodulator whose operation is based on the multiphase comparison of charging times of integrated capacitors. The described FSK demodulator approach removes deleterious effects resulting from low-frequency changes in the transmitter frequency, and eliminates time distortion artifacts generated by circuit imbalances and asymmetries in the power recovery process. The combination of the transmitter and receiver improvements yields a reliable data transfer system unaffected by circuit imbalances and incidental variations in the amplitude and frequency of the magnetic field.

A modulator (10) and method provides a programmable phase rotation for supporting different modulation formats and different phase rotations. The modulator (10) includes a programmable symbol counter (32) and symbol phase rotation logic (31) operatively responsive to programmable phase rotation size data (36) and programmable counter size data (30). The modulator (10) can be used to communicate with different modulation formats employing different phase rotation conventions as used in different communication systems. The symbol phase rotation logic (31) produces rotated in-phase data (20) and rotated quadrature data (22) in response to receiving at least received symbol data (24), programmable phase rotation size data (36), and symbol count data (32) based on programmable counter size data (30). According to another embodiment, the phase rotations of the modulator (10) may be dynamically selectable such that the phase rotations may be selected to accommodate changes in channel characteristics in real time.

A method is provided for correcting a quadrature angle error that exists in the coherent receiver hardware of a dual-polarization optical transport system. The receiver hardware that causes the quadrature angle error is a 90 degree optical hybrid mixing device. The method involves generating an estimate of the quadrature angle error and compensating for the quadrature angle error by multiplying the first and second detected baseband signals by coefficients that are a function of the estimate of the quadrature angle error. The method is robust to severe channel distortion encountered within an optical fiber transmission channel as well as temperature effects and ageing of the 90 degree optical hybrid. The method is suited for a digital signal processing implementation in the coherent receiver when a modulation scheme used on a transmitted signal is quadriphase-shift keying (QPSK). In other embodiments, the method can be used to correct for quadrature angle error in modulation schemes such as binary PSK, M-ary PSK where M>4, or Quadrature Amplitude Modulation (QAM). The method can be implemented by an application-specific integrated circuit(ASIC).

An apparatus and a method for a bias modulator using a Zero Current Switching (ZCS) are provided. The bias modulator includes a Pulse Width Modulation (PWM) signal generator for converting an input envelope signal to a PWM signal; a PWM/ZCS converter for calculating the number of ZCS control signals to be provided within an on-time duration of the PWM signal and generating at least one ZCS control signal according to the number of the ZCS control signals; and a ZCS switching regulator for generating a bias current according to the ZCS control signal.

A test apparatus includes digital modulators provided in increments of multiple channels. A baseband signal generator performs retiming of data input as a modulation signal for the in-phase (quadrature) component, using a timing signal the timing of which can be adjusted, thereby generating a baseband signal. A driver generates a multi-value digital signal having a level that corresponds to the baseband signal output from the baseband signal generator. A multiplier amplitude-modulates a carrier signal with the multi-value digital signal. An adder sums the output signals of the multipliers.

A method for generating/transmitting a transmission-unit symbol sequence is disclosed. In the case of transmission information, the information is modulated in time and frequency domains on the basis of a predetermined transmission unit (e.g., a transmission time interval TTI or slot), simultaneous transmission of the information is made, and then a transmission unit symbol is generated/transmitted. A transmission sequence is masked in each symbol contained in one transmission unit. Symbol-unit circular shift (cyclic shift) is applied to the masked result, so that transmission efficiency increases. A control signal transmission method for supporting a variety of formats and a signal transmission method based on a prime-length sequence are also provided.

The present invention provides an RF transmission leakage mitigator for use with a full-duplex, wireless transceiver. In one embodiment, the RF transmission leakage mitigator includes an inversion generator configured to provide an RF transmission inversion signal of an interfering transceiver RF transmission to a receiving portion of the transceiver thereby creating a residual leakage signal. Additionally, the RF transmission leakage mitigator also includes a residual processor coupled to the inversion generator and configured to adjust the RF transmission inversion signal of the interfering transceiver RF transmission based on reducing the residual leakage signal to a specified level.

A high data rate communication system operating at frequencies greater than 70 MHz and at data rates of about 1.25 Gbps or greater. Preferred embodiments include modulators with a resonant LC circuit including a diode which is back-biased for "off" (i.e., no transmit) and forward biased for "on" (or transmit). The modulator is a part of high performance transceivers for wireless, millimeter wave communications links. A preferred embodiment provides a communication link of more than eight miles which operates within the 71 to 76 GHz portion of the millimeter spectrum and provides data transmission rates of 1.25 Gbps with bit error rates of less than 10<-10 >. A first transceiver transmits at a first bandwidth and receives at a second bandwidth both within the above spectral range. A second transceiver transmits at the second bandwidth and receives at the first bandwidth. The transceivers are equipped with antennas providing beam divergence small enough to ensure efficient spatial and directional partitioning of the data channels so that an almost unlimited number of transceivers will be able to simultaneously use the same spectrum. In a preferred embodiment the first and second spectral ranges are 71.8+/-0.63 GHz and 73.8+/-0.63 GHz and the half power beam width is about 0.2 degrees or less. Preferably, a backup transceiver set is provided which would take over the link in the event of very bad weather conditions. In other embodiments especially useful for mobile applications at least one of the transceivers include a GPS locator.

Digital transmitters having improved characteristics are described. In one design of a digital transmitter, a first circuit block receives inphase and quadrature signals, performs conversion from Cartesian to polar coordinates, and generates magnitude and phase signals. A second circuit block (which may include a delta-sigma modulator or a digital filter) generates an envelope signal based on the magnitude signal. A third circuit block generates a phase modulated signal based on the phase signal. The third circuit block may include a phase modulating phase locked loop (PLL), a voltage controlled oscillator (VCO), a saturating buffer, and so on. A fourth circuit block (which may include one or more exclusive-OR gates or an amplifier with multiple gain states) generates a digitally modulated signal based on the envelope signal and the phase modulated signal. A fifth circuit block (which may include a class D amplifier and/or a power amplifier) amplifies the digitally modulated signal and generates an RF output signal.

A receiver operatively coupled to an antenna structure capable of receiving a first plurality of RF signals is disclosed herein. The receiver includes an RF processing network operative to perform weighting and combining operations within the RF domain using the first plurality of RF signals so as to produce a second plurality of RF signals. Also provided is a downconverter configured to downconvert the second plurality of RF signals into a second plurality of down-converted signals. In alternate implementations certain of the weighting and combining operations are performed at baseband and the remainder effected within the RF domain. A transmitter of corresponding architecture is also disclosed.

An adjustable chaotic signal generator using pulse modulation for UWB communications, and a chaotic signal generating method thereof are provided. The chaotic signal generator for UWB communications includes a plurality of pulse generators which generates pulses of different frequencies; at least one combiner which combines the pulses generated at the pulse generators; and a plurality of local oscillators which receives signals from the combiner, respectively, and generates a chaotic signal by increasing the received signals to different frequency bands. Accordingly, a plurality of users can conduct the radio communications in a specific wireless communication range at the same time by generating the chaotic signal that can be split to the multiple channels. Also, the chaotic signal generator is structured using devices integratable on an integrated circuit.